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Beego/vendor/github.com/siddontang/rdb/loader.go
2018-07-30 12:05:51 +08:00

113 lines
2.2 KiB
Go

// Copyright 2014 Wandoujia Inc. All Rights Reserved.
// Licensed under the MIT (MIT-LICENSE.txt) license.
package rdb
import (
"bytes"
"encoding/binary"
"fmt"
"hash"
"io"
"strconv"
)
type Loader struct {
*rdbReader
crc hash.Hash64
db uint32
}
func NewLoader(r io.Reader) *Loader {
l := &Loader{}
l.crc = newDigest()
l.rdbReader = newRdbReader(io.TeeReader(r, l.crc))
return l
}
func (l *Loader) LoadHeader() error {
header := make([]byte, 9)
if err := l.readFull(header); err != nil {
return err
}
if !bytes.Equal(header[:5], []byte("REDIS")) {
return fmt.Errorf("verify magic string, invalid file format")
}
if version, err := strconv.ParseInt(string(header[5:]), 10, 64); err != nil {
return err
} else if version <= 0 || version > Version {
return fmt.Errorf("verify version, invalid RDB version number %d", version)
}
return nil
}
func (l *Loader) LoadChecksum() error {
crc1 := l.crc.Sum64()
if crc2, err := l.readUint64(); err != nil {
return err
} else if crc1 != crc2 {
return fmt.Errorf("checksum validation failed")
}
return nil
}
type Entry struct {
DB uint32
Key []byte
ValDump []byte
ExpireAt uint64
}
func (l *Loader) LoadEntry() (entry *Entry, err error) {
var expireat uint64
for {
var otype byte
if otype, err = l.readByte(); err != nil {
return
}
switch otype {
case rdbFlagExpiryMS:
if expireat, err = l.readUint64(); err != nil {
return
}
case rdbFlagExpiry:
var sec uint32
if sec, err = l.readUint32(); err != nil {
return
}
expireat = uint64(sec) * 1000
case rdbFlagSelectDB:
if l.db, err = l.readLength(); err != nil {
return
}
case rdbFlagEOF:
return
default:
var key, obj []byte
if key, err = l.readString(); err != nil {
return
}
if obj, err = l.readObject(otype); err != nil {
return
}
entry = &Entry{}
entry.DB = l.db
entry.Key = key
entry.ValDump = createValDump(otype, obj)
entry.ExpireAt = expireat
return
}
}
}
func createValDump(otype byte, obj []byte) []byte {
var b bytes.Buffer
c := newDigest()
w := io.MultiWriter(&b, c)
w.Write([]byte{otype})
w.Write(obj)
binary.Write(w, binary.LittleEndian, uint16(Version))
binary.Write(w, binary.LittleEndian, c.Sum64())
return b.Bytes()
}